Sense 43912 225701296 2008-07-14T23:50:36Z Jwinius 141528 /* Vision */ Edits to snake wlinks, adding pythons. {{this|the senses of living organisms (vision, taste, etc.)}} [[Image:1668 Gérard de Lairesse - Allegory of the Five Senses.jpg|thumb|right|Depictions of the five senses became a popular subject for seventeenth-century artists, especially among [[Dutch Golden Age painting|Dutch]] and [[Flemish Baroque painter]]s. A typical example is [[Gérard de Lairesse]]'s ''Allegory of the Five Senses'' (1668; [[Kelvingrove Art Gallery and Museum]]), in which each of the figures in the main group allude to a sense: sight is the reclining boy with a [[convex mirror]], hearing is the [[cupid]]-like boy with a [[Triangle (instrument)|triangle]], smell is represented by the girl with flowers, taste by the woman with the fruit and touch by the woman holding the bird.]] '''Senses''' are the physiological methods of [[perception]]. The senses and their operation, classification, and theory are overlapping topics studied by a variety of fields, most notably [[neuroscience]], [[cognitive psychology]] (or [[cognitive science]]), and [[philosophy of perception]]. The [[nervous system]] has a specific [[sensory system]], or organ, dedicated to each sense. ==Definition of sense== There is no firm agreement among neurologists as to the number of senses because of differing definitions of what constitutes a sense. One definition states that an exteroceptive sense is a faculty by which outside stimuli are perceived.<ref>[http://www.eioba.com/a70192/senses Senses<!-- Bot generated title -->]</ref> The traditional '''five senses''' are sight, hearing, touch, smell, taste: a classification attributed to [[Aristotle]].<ref>[http://www.jewishencyclopedia.com/view.jsp?artid=479&letter=S JewishEncyclopedia.com - SENSES, THE FIVE<!-- Bot generated title -->]</ref> Humans also have at least six additional senses (a total of eleven including interoceptive senses) that include: [[nociception]] (pain), [[equilibrioception]] (balance), [[proprioception]] & [[kinesthesia]] (joint motion and acceleration), [[sense of time]], [[thermoception]] (temperature differences), and in some a weak [[magnetoception]] (direction)<ref>Magnetic fields and the central nervous system, ''Clinical Neurophysiology'', Volume 111, Issue 11, Pages 1934 - 1935, A . Voustianiouk</ref>. One commonly recognized catagorisation for human senses is as follows: [[chemoreception]]; [[photoreception]]; [[mechanoreception]]; and [[thermoception]]. Indeed, all human senses fit into one of these four categories. Different senses also exist in other organisms, for example [[electroreception]]. A broadly acceptable definition of a sense would be "a system that consists of a group sensory cell types that responds to a specific physical phenomenon, and that corresponds to a particular group of regions within the brain where the [[Signalling theory|signal]]s are received and interpreted." Disputes about the number of senses arise typically regarding the classification of the various cell types and their [[Mind map|mapping]] to regions of the brain. ==Senses== ===Sight=== '''[[Visual perception|Sight]]''' or '''vision''' is the ability of the brain and eye to detect electromagnetic waves within the visible range ([[light]]) interpreting the image as "sight." There is disagreement as to whether this constitutes one, two or three senses. Neuroanatomists generally regard it as two senses, given that different receptors are responsible for the perception of colour (the frequency of photons of light) and brightness (amplitude/intensity - number of photons of light). Some argue{{Fact|date=December 2007}} that [[stereopsis]], the perception of depth, also constitutes a sense, but it is generally regarded as a cognitive (that is, post-sensory) function of brain to interpret sensory input and to derive new information. The inability to see is called [[blindness]]. ===Hearing=== '''[[Hearing (sense)|Hearing]]''' or '''audition''' is the sense of [[sound]] perception. Since sound is vibrations propagating through a medium such as air, the detection of these vibrations, that is the sense of the hearing, is a mechanical sense akin to a sense of touch, albeit a very specialized one. In humans, this perception is executed by tiny hair fibres in the inner [[ear]] which detect the motion of a membrane which vibrates in response to changes in the pressure exerted by atmospheric particles within a range of 20 to 22000&nbsp;Hz, with substantial variation between individuals. Sound can also be detected as vibrations conducted through the body by tactition. Lower and higher frequencies than that can be heard are detected this way only. The inability to hear is called [[Hearing impairment|deafness]]. ===Taste=== {{Citations missing|date=March 2008}} '''[[Taste]]''' or '''gustation''' is one of the two main "chemical" senses. There are at least four types of tastes[http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/T/Taste.html] that "buds" (receptors) on the [[tongue]] detect, and hence there are anatomists who argue{{Fact|date=March 2008}} that these constitute five or more different senses, given that each receptor conveys information to a slightly different region of the brain{{Fact|date=March 2008}}. The inability to taste is called [[ageusia]]. The four well-known receptors detect sweet, salt, sour, and bitter, although the receptors for sweet and bitter have not been conclusively identified. A fifth receptor, for a sensation called ''[[umami]]'', was first theorised in 1908 and its existence confirmed in 2000<ref>[http://www.nature.com/neuro/press_release/nn0200.html Press Releases - Nature Neuroscience<!-- Bot generated title -->]</ref>. The umami receptor detects the [[amino acid]] glutamate, a flavor commonly found in meat and in artificial flavourings such as monosodium glutamate. Note that taste is not the same as [[flavor]]; flavor includes the [[smell]] of a food as well as its taste. ===Smell=== '''[[Olfaction|Smell]]''' or '''olfaction''' is the other "chemical" sense. Unlike taste, there are hundreds of olfactory receptors, each binding to a particular molecular feature. Odor molecules possess a variety of features and thus excite specific receptors more or less strongly. This combination of excitatory signals from different receptors makes up what we perceive as the molecule's smell. In the brain, olfaction is processed by the [[olfactory system]]. [[Olfactory receptor neuron]]s in the [[nose]] differ from most other neurons in that they die and regenerate on a regular basis. The inability to smell is called [[anosmia]]. ===Touch=== '''[[Somatosensory system|Touch]]''', also called '''[[tactition]]''', '''mechanoreception''' or '''somatic sensation''', is the sense of '''pressure''' perception, generally in the [[skin]]. There are a variety of [[mechanoreceptor|nerve endings]] that respond to variations in pressure (e.g., firm, brushing, and sustained). The inability to feel anything or almost anything is called [[anesthesia]]. [[Paresthesia]] is a [[sensation]] of tingling, pricking, or [[numbness]] of a [[person]]'s [[skin]] with no apparent long term physical effect. ===Balance and acceleration=== '''[[Balance]]''', '''[[Equilibrioception]]''', or '''vestibular sense''', is the sense which allows an organism to sense body movement, direction, speed, and acceleration, and to attain and maintain postural [[equilibrium]] and balance. The organ of equilibrioception is the vestibular labyrinthine system found in both of the [[inner ear]]s. Technically this organ is responsible for two senses, [[angular momentum]] and [[linear acceleration]] (which also senses [[gravity]]), but they are known together as equilibrioception. The [[vestibular nerve]] conducts information from the three [[semicircular canal]]s, corresponding to the three spatial planes, the [[utricle]], and the [[saccule]]. The [[ampulla]], or base, portion of the three semicircular canals each contain a structure called a [[crista]]. These bend in response to angular momentum or spinning. The saccule and utricle, also called the "[[otolith]] organs", sense linear acceleration and thus gravity. Otoliths are small crystals of [[calcium carbonate]] that provide the inertia needed to detect changes in acceleration or gravity. ===Temperature=== '''[[Thermoception]]''' is the sense of '''heat''' and the absence of heat ('''cold''') by the [[skin]] and including internal skin passages. The thermoceptors in the skin are quite different from the [[homeostasis|homeostatic]] thermoceptors in the brain ([[POAH|hypothalamus]]) which provide feedback on internal body temperature. ===Kinesthetic sense=== '''[[Proprioception]]''', the '''kinesthetic sense''', provides the parietal cortex of the brain with information on the relative positions of the parts of the body. Neurologists test this sense by telling patients to close their eyes and touch the tip of a finger to their nose. Assuming proper proprioceptive function, at no time will the person lose awareness of where the hand actually is, even though it is not being detected by any of the other senses. Proprioception and touch are related in subtle ways, and their impairment results in surprising and deep deficits in perception and action. <ref>http://www.roblesdelatorre.com/gabriel/GR-IEEE-MM-2006.pdf Robles-De-La-Torre 2006</ref> ===Pain=== '''[[Pain and nociception|Nociception]]''' (physiological pain) signals near-damage or damage to tissue. The three types of pain receptors are cutaneous (skin), somatic (joints and bones) and visceral (body organs). It was believed that pain was simply the overloading of pressure receptors, but research in the first half of the 20th century indicated that pain is a distinct phenomenon that intertwines with all of the other senses, including touch. Pain was once considered an entirely subjective experience, but recent studies show that pain is registered in the [[anterior cingulate gyrus]] of the brain. === Other internal senses === An '''internal sense''' or interoception is "any sense that is normally stimulated from within the body."<ref>Dorland's Medical Dictionary 26th edition, under sense</ref> These involve numerous sensory receptors in internal organs, such as [[stretch receptor]]s that are neurologically linked to the brain. * [[Pulmonary stretch receptors]] are found in the lungs and control the [[respiratory rate]]. * [[Cutaneous receptor]]s in the skin not only respond to touch, pressure, and temperature, but also respond to vasodilation in the skin such as [[Flushing (physiology)| blushing]]. * Stretch receptors in the [[gastrointestinal tract]] sense gas distension that may result in colic pain. * Stimulation of sensory receptors in the esophagus result in sensations felt in the throat when [[swallowing]], [[vomiting]], or during [[acid reflux]]. * Sensory receptors in [[pharynx]] mucosa, similar to touch receptors in the skin, sense foreign objects such as food that may result in a [[gagging]] reflex and corresponding gagging sensation. * Stimulation of sensory receptors in the [[urinary bladder]] and [[rectum]] may result in sensations of fullness. * Stimulation of stretch sensors that sense dilation of various blood vessels may result in pain, for example headache caused by vasodilation of brain arteries. == Non-human senses == ===Analogous to human senses=== Other living organisms have receptors to sense the world around them, including many of the senses listed above for humans. However, the mechanisms and capabilities vary widely. ====Smell==== Among non-human species, [[dog]]s have a much keener sense of smell than humans, although the mechanism is similar. [[Insect]]s have olfactory receptors on their [[Antenna (biology)|antennae]]. ====Vision==== [[Cats]] have the ability to see in the dark due to muscles surrounding their irises to contract and expand pupils as well as the [[tapetum lucidum]], a reflective membrane that optimizes the image. [[Crotalinae|Pitvipers]], [[Pythonidae|pythons]] and some [[Boidae|boa]]s have organs that allow them to detect [[infrared]] light, such that these snakes are able to sense the body heat of their prey. The [[common vampire bat]] may also have an infrared sensor on its nose.<ref>{{cite web|url=http://www.pitt.edu/AFShome/s/l/slavic/public/html/courses/vampires/images/bats/vambat.html|title=www.pitt.edu/AFShome/s/l/slavic/public/html/courses/vampires/images/bats/vambat.html<!--INSERT TITLE-->|accessdate=2007-05-25}}</ref> Infrared senses are, however, just sight in a different light frequency range. It has been found that [[birds]] and some other animals are [[tetrachromats]] and have the ability to see in the [[ultraviolet]] down to 300 nanometers. [[Bees]] are also able to see in the ultraviolet. ====Balance==== [[Ctenophores]] have a balance receptor (a [[statocyst]]) that works very differently from the mammalian's semi-circular canals. ===Not analogous to human senses=== In addition, some animals have senses that humans do not, including the following: *'''[[Electroception]] (or "electroreception")''', the most significant of the non-human senses, is the ability to detect [[electric field]]s. Several species of fish, [[shark]]s and rays have the capacity to sense changes in electric fields in their immediate vicinity. Some fish passively sense changing nearby electric fields; some generate their own weak electric fields, and sense the pattern of field potentials over their body surface; and some use these electric field generating and sensing capacities for social communication. The mechanisms by which electroceptive fish construct a spatial representation from very small differences in field potentials involve comparisons of spike latencies from different parts of the fish's body. :The only order of mammals that is known to demonstrate electroception is the [[monotreme]] order. Among these mammals, the [[platypus]]<ref>[http://web.archive.org/web/19981206164009/http://instruct1.cit.cornell.edu/courses/bionb420.07/anelson/platypus.html Electroreception in the Platypus<!-- Bot generated title -->]</ref> has the most acute sense of electroception. :[[Body modification]] enthusiasts have experimented with magnetic implants to attempt to replicate this sense,<ref>{{cite web|url=http://www.boingboing.net/2005/05/05/implant_gives_artist.html|title=Implant gives artist the sense of "magnetic vision" |accessdate=2007-05-25}}</ref> however in general humans (and probably other mammals) can detect electric fields only indirectly by detecting the effect they have on hairs. An electrically charged balloon, for instance, will exert a force on human arm hairs, which can be felt through tactition and identified as coming from a static charge (and not from wind or the like). This is however not electroception as it is a post-sensory cognitive action. *'''[[Animal echolocation|Echolocation]]''' is the ability to determine orientation to other objects through interpretation of reflected sound (like [[sonar]]). [[Bat]]s and [[cetacea]]ns are noted for this ability, though some other animals use it, as well. It is most often used to navigate through poor lighting conditions or to identify and track prey. There is currently an uncertainty whether this is simply an extremely developed post-sensory interpretation of auditory perceptions or it actually constitutes a separate sense. Resolution of the issue will require brain scans of animals while they actually perform echolocation, a task that has proven difficult in practice. Blind people report they are able to navigate by interpreting reflected sounds (esp. their own footsteps), a phenomenon which is known as [[Human echolocation]]. *'''[[Magnetoception]] (or "magnetoreception")''' is the ability to detect fluctuations in [[magnetic field]]s and is most commonly observed in [[bird]]s, though it has also been observed in insects such as [[bee]]s. Although there is no dispute that this sense exists in many [[avian]]s (it is essential to the navigational abilities of migratory birds), it is not a well-understood phenomenon<ref>[http://www.ks.uiuc.edu/Research/magsense/ms.html The Magnetic Sense of Animals<!-- Bot generated title -->]</ref>. There is experimental and physical evidence to suggest this sense exists in a weak form in humans{{Fact|date=March 2008}}. :[[Magnetotactic bacteria]] build miniature magnets inside themselves and use them to determine their orientation relative to the Earth's magnetic field. *'''Pressure detection''' uses the '''[[lateral line]]''', which is a pressure-sensing system of hairs found in fish and some aquatic [[amphibia]]ns. It is used primarily for navigation, hunting, and schooling. Humans have a basic relative-pressure detection ability when eustachian tube(s) are blocked, as demonstrated in the ear's response to changes in altitude. *'''[[Polarized light]] direction / detection''' is used by [[bees]] to orient themselves, especially on cloudy days. [[Cuttlefish]] can also perceive the polarization of light. ==See also== * [[Attention]] * [[Auditory illusion]], [[Optical illusion]], [[Touch illusion]] * [[Basic taste]]s * [[Communication]] * [[Empiricism]] * [[intuition (knowledge)|Intuition]] * [[Sensation]] * [[Multimodal integration]] * [[Sensitivity (human)]] * [[Sense of time]] * [[Sensorium]] * [[Synesthesia]] ===Research Centers=== * [[Howard Hughes Medical Institute]] (HHMI) * [[Institute for Advanced Science & Engineering]] (IASE) ==References== <references/> ==External links== * The 2004 [[Nobel Prize]] in [[Nobel Prize in Physiology or Medicine|Physiology or Medicine]] ([http://nobelprize.org/medicine/laureates/2004/index.html announced] [[4 October]] [[2004]]) was won by [[Richard Axel]] and [[Linda Buck]] for their work explaining olfaction, published first in a joint paper in 1991 that described the very large family of about one thousand genes for odorant receptors and how the receptors link to the brain. * [http://www.hhmi.org/senses/ [[Howard Hughes Medical Institute|HHMI]] - World renowned centre of medical excellence] * [http://www.senses.info [[Institute for Advanced Science & Engineering|IASE]] - senses.info] - A research center that focuses on the basis of senses. * [http://www.scribd.com/doc/32909/Sensing-or-feeling/ Answers to several questions related to senses and human feeling from curious kids] * [http://www.physpharm.fmd.uwo.ca/undergrad/sensesweb The Physiology of the Senses tutorial] 12 animated chapters on vision, hearing, touch, balance and memory. {{Sensory system}} [[Category:Sensory system]] [[Category:Perception]] [[ca:Sentit]] [[cs:Smysl (biologie)]] [[da:Sans (organisme)]] [[de:Sinn (Wahrnehmung)]] [[es:Sentido]] [[eo:Senso]] [[fr:Sens (physiologie)]] [[ko:감각]] [[io:Senso]] [[id:Indera]] [[is:Skynfæri]] [[it:Organi di senso]] [[he:חוש]] [[nl:Zintuig]] [[ja:感覚]] [[pl:Zmysł]] [[pt:Sentido]] [[ru:Ощущение]] [[simple:Sense]] [[fi:Aisti]] [[sv:Sinne]] [[tr:Duyu]] [[wa:Cénk sinses]] [[yi:שפיראכץ]] [[zh:感官]]